Fundamental to the success of forest restoration following major disturbances such as mining is development of a functioning soil, including the amount, properties and rates of accumulation of soil organic matter (SOM). SOM enters mineral soil through leaching of dissolved organic matter from the forest floor; macrofaunal processing of above-ground litter and mixing with soil (bioturbation); and direct deposition of root litter and rhizodeposits. Our study focused on how SOM accumulation in reclaimed mineral soils was affected following re-vegetation with three vegetation treatments: deciduous trees (Populus tremuloides Mitchx. and Populus balsamifera L.), spruce trees (Picea glauca (Moench) Voss.) and grasses (Festuca sp., Bromus inermis), compared to the natural boreal forest. Seventeen sites were studied: 4 reclaimed Deciduous, 5 reclaimed Spruce, 4 reclaimed Grass, and 4 Natural forest. Concentrations of soil organic matter in the upper 30 cm of soil were highest at the Deciduous sites and lowest at Natural sites. SOM concentrations in the top 10 cm of soil were elevated relative to 10–30 cm soil at the Deciduous and Grass sites. The elevated SOM in the upper soil at Deciduous and Grass sites was associated with greater macrofauanal activity and higher root biomass at these sites. The higher macrofaunal activity in the surface organic layer and greater amounts of faunal fecal material in the uppermost cm of soil at Deciduous and Grass sites indicate greater enrichment of upper soil by macrofauna at these sites. SOM concentrations were significantly positively related to root abundance at Grass sites (indicating a contribution of roots to SOM), and a similar trend was apparent at the Deciduous sites. The elevated organic matter concentrations in the upper 10 cm of soil at the Deciduous and Grass sites suggest that planting of aspen following reclamation would hasten C sequestration into soil organic matter.